Ink jet printing is a conventional technique by which printing is accomplished without contact between the printing apparatus and the substrate, or medium, on which the desired print characters are deposited. Such printing is accomplished by ejecting ink from an ink jet printhead of the printing apparatus via numerous methods which employ, for example, pressurized nozzles, electrostatic fields, piezo-electric elements and/or heaters for vapor phase droplet formation.
Recently there has been a desire for a hand-held printer, which utilizes the same ink jet printing technology. One embodiment of this hand-held printer is an ink jet pen. The ink jet pen utilizes a printhead to deposit ink on a substrate rather than utilizing a conventional ballpoint roller or felt tip marker of a conventional pen. A user of the ink jet pen activates the pen to begin writing and moves the ink jet pen in a similar motion as a user would move a conventional pen to deposit ink on the substrate. It is desired that the ink jet pen be similar in shape and/or size to a conventional pen to allow the user to efficiently and effectively use the ink jet pen for writing. Accordingly, the conventional components of ink jet printing must be miniaturized to fit in the conventional long and slender shape of a pen.
Thus, ink reservoirs of the hand-held ink jet pen differ from conventional ink jet printer cartridge ink reservoirs in their shape and size. Since the size of the ink jet pen is desired to be limited, the overall efficiency of the ink jet system is desired to be increased. One potential drawback of a long and slender reservoir is that it deviates from the spherical shape which theoretically holds the largest amount of ink for a small surface area. One solution known in the art to attempt to overcome this opportunity for improvement is to increase the efficiency of the reservoir material which produces a negative pressure to avoid drooling of the ink. However, there potentially remains a substantial quantity of ink stranded in the reservoir material which can affect the page yield of the ink reservoir and therefore the overall efficiency of the ink jet pen. As such, there is a need for an ink jet pen with increased efficiency in overall yield from the ink reservoir. Accordingly, improved ink jet pens are desired.